Stability of liquid crystalline

Hur S-T, Gim M-J, Yoo H-J, Choi S-W, Takezoe H (2011) Enhanced thermal stability of liquid crystalline blue phase I with decreasing bend and splay elastic constant ratio K33/K11. Soft Matter, in press (DOI 10.1039/clsm06046e)... 

The section commences with monosubstituted ferrocene derivatives, after which the influence of the substitution pattern on the formation and stability of liquid-crystalline phases for disub-stituted ferrocene derivatives will be discussed. Next, the influence of the three-dimensional structure of ferrocene on the mesomorphic properties will be highlighted, optically active ferrocene materials will be described and, finally, ferrocene-containing liquid-crystalline dendrimers will be introduced ferrocene-containing liquid-crystalline polymers will not be reported. Note that a review devoted to ferrocene-containing thermotropic liquid crystals has already been published. ... 

THE EFFECT OF THE CHEMICAL STRUCTURE ON THE STABILITY OF LIQUID CRYSTALLINE STATE... 

At first,we studied the effect of the chemical structure of polymer chain on the stability of liquid crystalline state.The liquid crystalline state of polyether-esters derived from substituted hydroquinone and substituted 1,2-bis(phenoxy) ethane-4,4 -dicarboxylic acid could be controled by the... 

We clarified the reason of the lower Tm of Me-HQ/BB than that of Me-HQ/TA by investigating the stability of liquid crystalline state of the model compounds derived from BB and TA as shown in Fig. l.The reason that Me-HQ/BB showed lower Tm is probably the lower enthalpy of Me-HQ/BB due to the twisted chemical structure of biphenylene unit as reported by K.Tashiro (4). ... 

Fig. 1 Stability of liquid crystalline model compounds derived from BB and TA.

PEC or tBu-HQ/PEC showed the moduli of 26 and 36 GPa, respectively which were lower than those of Me-HQ/PEC or Cl-HQ/ PEC because of their decreased stability of liquid crystalline state by the presence of the bulky substituent as shown in Fig. 

In order to obtain high modulus as-spun fibers,the stability of liquid crystalline state and the rigidity of polymer chain are influential factors.Therefore,we expected that the polyarylates derived from BB would show higher modulus than those from PEC or Cl-PEC.As-spun fiber of the polyarylate derived from Cl-HQ and BB modified with TA(Cl-HQ/BB/TA) showed the modulus of 95 GPa(m/n= 7/3) which was higher modulus compared with that of Me-HQ/Cl-PEC. However,as-spun fiber of Cl-HQ/BB/TA showed the modulus of only 11 GPa(m/n=8/2) in spite of the rigid chemical structure,and this is referred to the decreased elongational flow orientation as shown in Fig. 4(3). 

Pearson, J. T. and Smith, J. M., Effect of hydrotropic salts on the stability of liquid crystalline systems, J. Pharm. Pharmacol, 26, (Suppl.), 123-124 (1974). 

The thermal stability of liquid crystalline polymers can also be studied using X-ray scattering method. The powder X-ray diffraction data for the above polymer system annealed at different temperatures are shown in Figures 5.16 and 5.17. Although the polymer is a monotropic liquid crystalline polymer, at 145°C, the liquid crystalline phase is fairly stable, while at lower temperature, the polymer crystallizes and loses its mesophase character within a few minutes of annealing. 

In order to synthesize liquid crystals with predicted properties, one of the basic questions for the chemist is Which intermolec-ular interactions are responsible for the stabilization of liquid crystalline phases The known dependence of mesogenity on the molecular geometry prompted the derivation of molecular-statistical theories, based on the shape-induced anisotropy of the repulsion of the molecules [25], Despite the remarkable success of such theories, it is clear that real condensed phases always eon-tain strong attraetive interactions, which are completely neglected by this procedure. Therefore, attempts have been made to... 

The induction or stabilization of liquid-crystalline phases in binary CT systems, where the donor and the acceptor compounds are rod-shaped, has been utilized in the design of polymers to enhance their mesomorphic properties the combination of mesomorphic properties and those of polymeric systems, e.g., glassy behavior, has attracted interest due to possible applications, for example, in the field of nonlinear optics. Side-chain copolymers with a polyester or polyacrylate backbone containing 4-me-thoxyazobenzene and 4-cyanoazobenzene units, for example, show the formation of an SmA phase with an enhanced mesomorphic temperature range [30]. Similar behavior is observed for copolystyrene derivatives carrying electron-rich donor units (4-methoxy-... 

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